[Users] iptables connlimit module not working

[Dan Bassett]

I just tested this out again on a newly installed machine.  I have the 
following in my vz.conf:

IPTABLES="ipt_REJECT ipt_tos ipt_limit ipt_multiport iptable_filter 
iptable_mangle ipt_TCPMSS ipt_tcpmss ipt_ttl ipt_length ipt_LOG 
ipt_conntrack ipt_state xt_connlimit ipt_connlimit"

IPTABLES_MODULES="$IPTABLES"

I have tried just "ipt_connlimit", just "xt_connlimit, and both in the 
IPTABLES list.  I even rebooted the machine before I started each test.  
I get the same results.  The connlimit rule is not tripped by multiple 
SSH connections as it should be.

Dan

On 06/21/2013 05:55 PM, Kir Kolyshkin wrote:
>
>
> On 21 June 2013 08:09, Dan Bassett <dbassett at oreillyschool.com 
> <mailto:dbassett at oreillyschool.com>> wrote:
>
>     I am running 2.6.32-042stab076.8 on a CentOS6 HN with CentOS6
>     containers, vzctl-4.2-1.x86_64. I have two containers running on
>     the same HN. Each CT has a veth device. Both CT's veth device is
>     connected to the same bridge device on the HN. They are assigned
>     the addresses 192.168.0.1/24 <http://192.168.0.1/24> and
>     192.168.0.2/24 <http://192.168.0.2/24> and can ping each other.
>
>     On the HN I am able to modprobe the connlimit module (xt_connlimit).
>
>
> You are supposed to load it before loading VZ modules (and this is the 
> reason of having it listed in vz.conf so vz initscript takes care of 
> loading it.
>
> If you loaded it after loading vz modules it might not work. So, to 
> make sure you'd do a reboot (or reloading of all vz modules -- 
> /etc/init.d/vz stop, then make sure vz modules such as vznet are not 
> loaded, then /etc/init.d/vz start).
>
>     I can then use iptables rules on the hostnode such as:
>
>     iptables -A INPUT -p tcp --syn --dport 22 -m connlimit
>     --connlimit-above 1 --connlimit-mask=32 -j REJECT
>
>     If I then attempt to initiate more than one ssh session to this HN
>     from the same host, the second (and all subsequent) ssh
>     connections are rejected.  This leads me to believe that the
>     connlimit module is working properly with the OpenVZ kernel.
>
>     I am able to successfully insert the same rule into the iptables
>     configuration in either of my containers, so it seems that the
>     xt_connlimit module is properly loaded (I get errors if I try to
>     use an iptables module that has not been loaded on the hostnode).
>      However, I can create more than one successful ssh session,
>     meaning that the iptables rule in the CT is not being matched for
>     some reason. I have both "xt_limit" and "xt_connlimit" in the list
>     of iptables modules to load in vz.conf. When I am running these
>     tests, I have no iptables rules loaded on the HN, and I have no
>     other iptables rules loaded in the container.
>
>     One interesting thing I have noticed is that when I enter a
>     container on this hostnode, I get the following errors:
>
>     [root at hn0 ~]# vzctl enter 2033892
>     Warning: Unknown iptable module: xt_connlimit, skipped
>     Warning: Unknown iptable module: xt_limit, skipped
>
>     It seems like this might be related to my issue, but it might just
>     be a red herring.
>
>
>
> This warning is harmless, it is not a bug, details are here:
> http://git.openvz.org/?p=vzctl;a=commit;h=d284c8a7
>
> Or see vz.conf(5) man page, description of IPTABLES and IPTABLES_MODULES.
>
>
>     Am I missing something obvious here? Or is this a bug with OpenVZ?
>
>     Thanks,
>     Dan
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>
>
>
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